Why Does Algae Grow on Patios?
Posted November 17, 2017

Algae growth can give an aesthetically pleasing, aged and ancient look to timbers and stones (think Japanese gardens and ancient forests). But when it grows on your patio it can just become more of a nuisance. Typically algae is slimy and slippery underfoot. Not only does it not look great, but it can actually be downright hazardous if left untreated for long periods of time.

So why do we get algae growth on our patios and stoned areas? And why do some places get it much worse than others?

There are a number of factors which encourage the growth of algae:

Dampness – Algae thrives in damp areas and those with poor drainage. Algae needs lots of water to grow and reproduce, and since patios are generally made of stone this gives a good surface to grow on during periods of wet weather.

Shade – Algae also loves to grow in shady spots, where the sun wont evaporate of the rain quickly, or dry out the newly forming algal spores.

Temperature and Humidity – While algae can grow year round, it is generally worse in the UK winter which is usually wet and fresh.

So if you have a shady paved area, say between a house and garage, where there isn’t great opportunity for drainage, chances are that come spring-time you will have a slippery green path that maybe looks something like the one on the right.

This area has all the classic problems that lead to a horrible green path. It’s in Ireland, so cool temperatures and lots of annual rainfall. Its a flat paved area with poor drainage and is shaded on both sides by the garage and the side-wall of the house itself. More of a slippery headache than a zen-garden, I think you’ll agree.

We will be treating this area with our Lancelot products, so check back later to see how we got on!